U.S. District Judge Michael McShane in Eugene ruled the voter-approved ban unconstitutionally discriminates against same-sex couples, and he ordered the state to stop enforcing it.

"I believe that if we can look for a moment past gender and sexuality, we can see in these plaintiffs nothing more or less than our own families," he wrote. "Families who we would expect our constitution to protect, if not exalt, in equal measure."

State officials earlier refused to defend Oregon's constitutional ban, and said they'd be prepared to carry out same-sex marriages almost immediately if McShane struck it down.

In Portland, couples lined up outside the Multnomah County clerk's office in anticipation of Monday's ruling. Among them were Laurie Brown and Julie Engbloom, who got engaged on their 10th anniversary in April.

The National Organization for Marriage sought to intervene in the cases brought by four gay and lesbian couples, and defend the ban on behalf of its Oregon members. But McShane rejected its request.

The group then appealed, and on Monday a three-judge panel of the 9th U.S. Circuit Court of Appeals denied its bid for an emergency stay.

McShane joins judges in seven other states who have struck down same-sex marriage bans, though appeals are underway.

Many predicted last year's Supreme Court ruling would create a pathway for states to act, as polls showed a majority of Americans now support gay marriage. Indeed, lower-court judges have repeatedly cited that decision when striking down bans.

Here's a closer look at where things stand across the country:

HOW MANY STATES ALLOW SAME-SEX MARRIAGE?

Gay and lesbian couples can legally marry in 17 states and the District of Columbia. The two most recent states to make the unions legal were New Mexico and Hawaii, both of which did so in late 2013. Oregon's ruling is not expected to be challenged, which would make it the 18th state where gay marriage is legal.

HOW MANY STATES ARE CONSIDERING MAKING GAY MARRIAGE LEGAL?

In 11 states, federal or state judges recently have overturned same-sex marriage bans or ordered states to recognize out-of-state marriages. Appeals courts are reviewing those decisions. Ten are in the hands of federal appeals courts, and one is with a state appeals court.

WHERE HAVE OTHER PRO-GAY MARRIAGE RULINGS COME DOWN?

They've been all over the country. Federal or state judges in Idaho, Oklahoma, Virginia, Michigan, Texas, Utah and Arkansas recently have found state same-sex marriage bans to be unconstitutional. Judges also have ordered Kentucky, Ohio, Tennessee and Indiana to recognize same-sex marriages from other states. The New Mexico Supreme Court declared the state ban unconstitutional in a ruling that is not being challenged.

Page 2 of 2 - IS OREGON'S ATTORNEY GENERAL THE ONLY ONE NOT DEFENDING A STATE BAN?

No. Oregon Attorney General Ellen Rosenblum is one of seven top state prosecutors who have refused to defend same-sex marriage bans in court. Attorney generals in Virginia, Pennsylvania, California, Illinois, Nevada and Kentucky, all Democrats, have made the same decision. Virginia and Kentucky still appealed rulings. A county clerk who was sued in Virginia is fighting that ban, and Kentucky hired outside attorneys.

WHAT DO OPPONENTS SAY?

Opposition remains stiff in many places, with critics pointing out that most states still prohibit gay marriage. They also note that in most states that do allow gay marriage, it was the work of courts or legislatures, not the people.

The Oregon Family Council released a strongly worded statement Monday saying the state colluded with gay-rights groups to sidestep the will of voters, and a judge allowed it.

"While tonight's newscast will feature tearful couples at staged PR activities in courthouses across the state, the real tears should be for the next generation as we witness our constitutional republic sink into a banana republic," spokeswoman Teresa Harke said.

DO OTHER STATES HAVE PENDING LAWSUITS?

Yes. At least 17 other states have filed lawsuits asking judges to throw out state bans. Only three states have no challenges pending: Montana, North Dakota and South Dakota. In addition, attorneys for gay couples in Nevada are challenging in a federal appeals court a 2012 ruling from a judge who upheld the state's same-sex marriage ban.

WHAT'S NEXT?

A ruling from a federal appeals court is expected soon, either from a panel in Denver reviewing rulings from Utah and Oklahoma or judges in Richmond, Virginia, reviewing Virginia's case. Many legal observers say they expect the U.S. Supreme Court to take a case at some point, but they acknowledge it's impossible to predict what the high court will do. The Supreme Court could also just wait and see how the nation's appellate courts rule. It often waits until there is a conflict between appellate courts before taking a case.